This invention relates to improved semiconductor capacitors that are particularly useful for manufacturing improved dynamic random access memory (DRAM), among other semiconductor devices.
Dynamic random access memory (DRAM) is well known in the art, the first commercially available DRAM having been the Intel 1103, introduced to the market in 1970. In a typical DRAM, information is stored in semiconductor capacitors on a metal oxide semiconductor (MOS) integrated circuit. Each semiconductor capacitor has a transistor associated with it, such that each transistor/capacitor combination forms a storage cell, or node, that can hold a single bit of information. Unfortunately, the capacitors leak so the storage nodes must be refreshed periodically. As these devices are scaled down to increasingly smaller sizes, the capacitance of the storage nodes is a limitation. There is a need for a method of increasing the capacitance of such storage nodes while also making them smaller.
Described is a method of increasing the topography of a semiconductor capacitor such as to effectively increase the capacitance of the capacitor without increasing the size of the capacitor. This is achieved by superimposing a topography, such as an array of holes or islands, onto the electrodes of the capacitor, wherein the elements of the topography (i.e., the holes or islands) are generally about an order of magnitude smaller than the capacitor itself.